Novel Eulerian Vorticity Transport Wake Module for Rotorcraft Flow Analysis

Accurate performance prediction is essential to the development of Army rotorcraft as well as the support of flight operations. While current numerical analysis tools can, in principle, model complete rotorcraft, in practice these implementations are severely hampered by accuracy limitations broadly attributed to modeling assumptions (e.g., vortex core models in Lagrangian methods) or numerical deficiencies (e.g. excessive numerical diffusion for Eulerian CFD). Thus, commonly used analysis tools fail to predict adequately the unsteady wakes and load distributions of rotor and fuselage designs. An approach that combines the first-principles physical modeling capability of Eulerian schemes with the vortex preservation capabilities of Lagrangian vortex techniques has long been needed. Enabled by recently-developed breakthrough technologies in Eulerian wake modeling that specifically address the critical numerical diffusion issue, this effort will develop a first-principles Eulerian vorticity transport wake module that will provide an unprecedented ability to capture the true temporal and spatial structure of the rotor wake when coupled to a wide range of CFD tools. In Phase I, a prototype wake module was developed and demonstrated through coupling to several representative CFD models. Phase II will see key enhancements, validation and packaging of a module with significantly expanded functionality tailored to Army needs.